At midnight on 14 December 1991, Aoraki Mount Cook was 3764 metres high. A few minutes later, a massive rock avalanche, at maximum rumble creating a magnitude 3.9 earthquake, had lowered New Zealand’s highest point by ten metres.
How long had the summit of Aoraki Mount Cook been ready to topple? For years, probably. The mountain’s glaciers are constantly eroding the slopes, deepening the valleys and steepening the mountainsides. The ice and snow crown the mountain with a tight cap, but they too add weight to the rock, and gravity keeps on pulling and pulling …
Suddenly, on a calm night, without even the hint of an earthquake to trigger a slide, the mountain top collapses.
At midnight on 14 December 1991, Aoraki Mount Cook was 3764
metres high. A few minutes later, a massive rock avalanche, at maximum rumble creating a magnitude 3.9 earthquake, had lowered New Zealand’s highest point by ten metres.
How long had the summit of Aoraki Mount Cook been ready to topple? For years, probably. The mountain’s glaciers are constantly eroding the slopes, deepening the valleys and steepening the mountainsides. The ice and snow crown the mountain with a tight cap, but they too add weight to the rock, and gravity keeps on pulling and pulling …
Suddenly, on a calm night, without even the hint of an earthquake to trigger a slide, the mountain top collapses.